Application of the Extended Porosity-deformation Approach to an HTI Shale Sample under Triaxial Stress Conditions

We use measurement results from ultrasonic laboratory experiments on a water-saturated vertically layered sample of the Norwegian shale published by Dewhurst et al.(2011) for the application of the porosity-deformation approach. In the first step, we show that the porosity-deformation approach describes well the hydrostatic stress dependency of the hydrostatic subset of data. In the next step, the obtained parameters and the porosity-deformation approach are used for computing theoretical predictions of the compliances S44 and S66 under triaxial stress conditions. The predicted results are in good agreement with the measurements. This shows an ability of the porosity-deformation approach to compute triaxial-stress dependent compliances using the rock properties obtained from a hydrostatic experiment.